1. Field of the Invention
This invention relates to a yarn cutting scissors device, and more particularly to a yarn cutting scissors device suitable for cutting a weft woven at a loom.
2. Description of the Prior Art
A typical yarn cutting scissors device which has been conventionally proposed and used in the art is disclosed in Japanese Utility Model Application Laid-Open Publication No. 145,583/1984. The scissors device taught in the publication is constructed in a manner such that a stationary blade or blade plate is mounted through a leaf spring on an end surface of a bearing block or support base and a movable blade is mounted through a leaf spring on a distal end of an oscillating shaft, so that both blades may be operated relatively to each other with the oscillation of the oscillating shaft to carry out the cutting of a yarn.
However, such construction of the conventional yarn cutting scissors device as described above has an important disadvantage that biasing forces generated from both leaf springs cause a large frictional force to occur at the edge portions of both blades successively engaged with each other in the cutting operation, resulting in the blades being highly damaged and worn.
Also, another disadvantage encountered with the conventional yarn cutting scissors device is that the generation of any looseness or backlash between both blades causes a gap to be formed therebetween, to thereby substantially deteriorate the sharpness or quality of the scissors. In order to prevent the generation of such looseness, a mechanism is proposed which is constructed in a manner such that an adjusting ring spacer is fittedly mounted on a rear end of the oscillating shaft projecting from the bearing block and supported by means of an E-shaped ring fixed on the oscillating shaft. Unfortunately, such mechanism proposed fails to fully absorb the losseness because it is highly troublesome or substantially impossible to precisely adjust the thickness of the ring spacer. Thus, the conventional yarn cutting scissors device requires another adjusting means for appropriately adjusting the engagement between both blades, resulting in the structure of the conventional yarn cutting scissors device being highly complicated and the manufacturing costs being substantially increased.
Accordingly, it would be highly desirable to develop a yarn cutting scissors device which is capable of decreasing a frictional force which occurs at the edge portions of both blades successively engaged with each other and accomplishing the effective engagement between both blades.